On the Relationship Between Coefficient Alpha and Composite Reliability

Peterson, Robert A.
Kim, Yeolib

¹Office of the Vice President for Research, The University of Texas at Austin

Robert A. Peterson, Office of the Vice President for Research, The University of Texas at Austin, Austin, TX 78712 [email protected]

Submission January 3, 2012. Revision October 1, 2012. Accepted October 2, 2012.

Journal of Applied Psychology 98(1):p 194-198, January 2013. | DOI: 10.1037/a0030767

Cronbach's coefficient alpha is the most widely used estimator of the reliability of tests and scales. However, it has been criticized as being a lower bound and hence underestimating true reliability. A popular alternative to coefficient alpha is composite reliability, which is usually calculated in conjunction with structural equation modeling. A quantitative analysis of 2,524 pairs of coefficient alpha and composite reliability values derived from empirical investigations revealed that although the average composite reliability value (.86) exceeded the average corresponding coefficient alpha value (.84), the difference was relatively inconsequential for practical applications such as meta-analysis.